Conventionally, a vehicle is equipped with a walk in mechanism for moving a front seat in forward direction in order to make the passenger easily entry on or off the rear seat of the vehicle by releasing a locking mechanism of a seat slide device, when the seatback (a back seat of the front seat) turns in forward direction.
An example of a seat device equipping a walk in mechanism is disclosed in a Japanese Patent Laid-Open Publication No. 2001-63410. This disclosed seat device has an upper rail being capable of sliding freely on a lower rail fixed to a vehicle floor in forward and backward directions. This seat device has a lock/unlock mechanism and usually maintains the seat device in a locking condition by fixing the upper and lower rails each other. The lock/unlock mechanism includes a side tooth (or a nail) of an operational handle supported in the upper rail side portion. The side tooth can engage with or disengage from a window provided in the lower rail. When the walk in mechanism is operated, the operational handle is moved and the side tooth is disengaged from the window, then the upper rail is made slidable on the lower rail in forward and backward directions.
In the foregoing disclosed publication, a supporting bracket is fixed to a top surface of an upper rail. A moving member is displaced to be capable of sliding in forward and backward directions relative to the supporting bracket. The moving member is maintained in the original position by a spring force. The moving member is connected to the seatback of the front seat by a cable.
When the seatback of the front seat is turned down in forward direction for easy entry of the passenger to the rear seat or getting out from the rear seat, the cable is pulled and the moving member is moved by the cable in the backward direction against the spring force on the top surface of the upper rail. In this way, due to the movement the moving member in the backward direction, the operational handle is moved and the side tooth thereof is disengaged from the window of the lower rail. Then the locking condition of the both rails is released. Therefore, the seat can be moved in forward or backward direction.
After the entry or getting out of the passenger to or from the rear seat is completed, in order to restore the seat to the original seating position, the walk in mechanism of the prior technology is provided with a memory mechanism including a finger member and a hook member installed on the moving member. In such a configurations, on the restoring process of the seating position to the original, the hook member engages with a hole formed on a plate fixed on the upper rail and maintains the moving member to disengage the side tooth from the window. And once the seat reaches at the original position, the engagement of the hook member with the upper rail is released by the operation of the finger member. The moving member is permitted to slide in forward direction and leaves from the operational handle to disengage the side tooth from the window of the lower rail. Then the lock condition between the upper rail and lower rail is also restored in the original position.
In the foregoing seat device, the hook device is pivotally supported on the moving member and to the upper rail, and engages with or disengages from the hole formed on the plate. For the smooth slide of the moving member on the upper rail, rather loose engagement between the moving member and the upper rail is required. This loose engagement, however, makes the hook position be unstable relative to the hole. This unstable engagement of the hook member to the hole of the metal plate may cause unstable position restoring operation.
In addition thereto, the movement of the moving member of the walk in mechanism on the one side of the seat device is transmitted to a latch member of the walk in mechanism on another side of the seat device by a connecting rod and long holes formed in levers attached on the both ends of the rod. The long holes engage with pins fixed on the moving members on the both side seat device. In this configuration, due to the rigidity of the rod and the gaps between the pins and the long holes, the movement transmission between the both of walk in mechanisms may be unstable and this may also cause unstable position restoring operation.
Therefore, the object of the present invention is to solve a disadvantageous point of the conventional technology described in the foregoing.